Broadband optical two-dimensional coherent spectroscopy of a rubidium atomic vapor

Optical two-dimensional coherent spectroscopy (2DCS) has become a powerful tool for studying energylevel structure, dynamics, and coupling in many systems including atomic ensembles. Various types of two-dimensional (2D) spectra, including the so-called single-quantum, zero-quantum, and double-quantum 2D spectra, of both D lines (D1 and D2 transitions) of potassium (K) atoms have been reported previously. For rubidium (Rb), a major difference is that the D lines are about 15 nm apart as opposed to only about 3 nm for K. Simultaneously exciting both D lines of Rb atoms requires a broader laser bandwidth for the experiment. Here, we report a broadband optical 2DCS experiment in a Rb atomic vapor. A complete set of single-quantum, zero-quantum, and double-quantum 2D spectra including both D lines of Rb atoms were obtained. The experimental spectra were reproduced by simulated 2D spectra based on the perturbation solutions to the optical Bloch equations. This work in Rb atoms complements previous 2DCS studies of K and Rb with a narrower bandwidth that covers two D lines of K or only a single D line of Rb. The broadband excitation enables the capability to perform double-quantum and multiquantum 2DCS of both D lines of Rb to study many-body interactions and correlations in comparison with K atoms.

Automated summary

Optical two-dimensional coherent spectroscopy (2DCS) is a useful tool for studying energy level structure and dynamics in atomic ensembles. In this study, a broadband optical 2DCS experiment was conducted on rubidium atoms, which have different D line characteristics compared to potassium atoms. The experimental results were consistent with simulated spectra based on the perturbation solutions. This work allows for the study of many-body interactions and correlations in rubidium atoms using double-quantum and multiquantum 2DCS.